Air samplers are finding increased application in a variety of uses. One such application deals with the transportation industry. For example, passengers may be subject to noxious smells or gases or other airborne impurities when traveling in enclosed vehicles such as trains, motor coaches, or airplanes.
When an event occurs during which passengers are subject to odors, smoke, gases, or other undesirable airborne impurities, it is desirable to perform some kind of test or sampling. The testing or sampling of the air supply may be done for several reasons. It may be desired to repeat the incident of impure air flow in order to sample the air and thus trace the source of impurity. Additionally, the testing or sampling may be performed in part to certify that, once corrected, the vehicle in question is again supplying clean air to passengers.
In the example of a modern passenger jetliner, air supply to the interior cabin often begins with the gas turbine engines. In the typical structure of a gas turbine engine, including those used in industrial, marine, vehicle, as well as aerojet applications, air enters the engine inlet and first passes through a series of compressor stages such as a low pressure stage and a high pressure stage. The air then passes through a combustion chamber and, in exiting the engine, crosses turbines such as high pressure and low pressure turbines. However, a significant portion of air that enters the engine inlet passes around the compressors, combustion chamber and turbines, this is called fan air. Additionally air in the compressors may be bled off for deicing and other pneumatic applications through bleed valves. Bleed valves are typically used to select air at a desired pressure within the gas turbine engine. Environmental control systems used in commercial airliners often draw air from either ram or the bleed valves. This air may then pass through ductwork, pumps, temperature controls, and other air handling equipment before being vented into the passenger cabin. In some applications, air may be extracted from a compressor which is not an integral part of an engine.
Present in these turbine propulsion engines as well as the APU's (auxiliary power units) are fluid sealing systems. Sealing systems typically work to contain materials such as lubricants and hydrocarbons within the engine body. For example sealing systems are employed within a gas turbine engine to prevent trace elements of materials such as fuel or lubricant from leaking from the engine and into the bleed air. However, such sealing systems are not always totally effective, and as a result there may be leakage of fuel or lubricant into the bleed air. Hence hydrocarbons and lubricants within the engine may often be a source of semivolatile compounds that result in odors and noxious impurities that are harmful or unpleasant to the passengers. Hydrocarbons for example can oxidize and produce smoke in the air flowing into the cabin.
Previous methods used to measure contaminants in engine bleed air have either been inconclusive or have given false readings. One such method incorporates a polyvinylchloride filter to collect a sample of the bleed air followed by looking for the presence of oil by using a black light to make the oil droplets fluoresce. Another method includes the use of a large, stainless steel coil chilled to about −100 degrees F. to condense matter in the bleed air. The condensed matter is then flushed from the coil, evaporated with a solvent (freon) and weighed. In a third method, the bleed air is flowed through absorption tubes in which residue is collected on silica gel, charcoal, or molecular sieves and then evaluated by gas chromatography/mass spectroscopy. The residue can also be analyzed by combusting its organic matter, and measuring the carbon dioxide formed with a flame ionization detector or nitrogen phosphorous detector.
Presently, there is no known equipment available that is designed to sample high volumes of air from a closed system. In particular there is no known equipment designed to take high volume air samples from the supply system of a closed aircraft fuselage. Accordingly there is a need for a high volume air sampler that can screen for particulate, volatile, and semivolatile materials present in the air sample.
In a closed environment, such as the fuselage interior of a commercial jet airplane, traditional methods of taking air samples face difficulties. In the typical known method for taking air samples a collector is exposed to the environment where it is desired to take an air sample. One end of the collector is open to the atmosphere and an opposite end of the collector is attached to a pump (typically with an intervening hose). Running the pump pulls a vacuum which serves to pull air through the collector.
The difficulty of such an arrangement in a closed environment is that current equipment is not designed to be used in a closed ducted system. Thus it is difficult to take air samples with this arrangement. However, low volume air samples are sometimes preferred when restricted power may require utilizing a battery power or similar low power vacuum pump. In such a case it is often necessary to sample a large volume of air over an extended period of time in order to capture a sufficient quantity of the contaminant in order to subject the impurity to analysis.
Low volume PUF samplers have also been used to capture semivolatile compounds in ambient air. As used in testing the air in an aircraft for airborne impurities, a low volume PUF sampler has a typical measuring sensitivity in the range of parts per million to high parts per billion, while being able to operate with a battery powered pump.
Recently it has been desired to collect air samples from specific locations within an aircraft body. However, no adapter has ever been invented which allows the capture of semivolatile organic compounds from remote locations utilizing the low volume PUF samplers. In the airline industry there is a need for an apparatus and method to take low volume air samples that may include semivolatile compounds. In particular, there is a need for an adapter that would allow sampling of semivolatile compounds using known sampling equipment such as a PUF sampler.
While apparatuses and methods of sampling semivolatile organic compounds are known; nevertheless, there is a need for an improved apparatus and method that overcomes one or more of the above-noted drawbacks. Namely, an apparatus is needed that will allow low volume sampling of semivolatile compounds in an enclosed environment such as the interior of an aircraft Further it is desired that the sampling method be able to collect air samples from specific locations with the airplane. It is also desired to collect samples from different locations within an airplane simultaneously. The PUF cartridge adapter disclosed herein addresses one of more of these needs.